svn-fe manual: Clarify warning about deltas in dump files

Those in the know would notice that dump file format version 2
means "svnadmin dump --no-deltas", but for the rest of us, an
explicit reminder is useful.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/contrib/svn-fe/svn-fe.txt b/contrib/svn-fe/svn-fe.txt
index fb0ee56..35f84bd 100644
--- a/contrib/svn-fe/svn-fe.txt
+++ b/contrib/svn-fe/svn-fe.txt
@@ -12,7 +12,7 @@
 DESCRIPTION
 -----------
 
-Converts a Subversion dumpfile (version: 2) into input suitable for
+Converts a Subversion dumpfile into input suitable for
 git-fast-import(1) and similar importers. REPO is a path to a
 Subversion repository mirrored on the local disk. Remote Subversion
 repositories can be mirrored on local disk using the `svnsync`
@@ -25,6 +25,9 @@
 Files in this format can be generated using the 'svnadmin dump' or
 'svk admin dump' command.
 
+Dumps produced with 'svnadmin dump --deltas' (dumpfile format v3)
+are not supported.
+
 OUTPUT FORMAT
 -------------
 The fast-import format is documented by the git-fast-import(1)